Method for making a rolling-lobe air spring and apparatus therefor and a rolling-lobe air spring having a flanged plate

ABSTRACT

A flanged plate ( 1 ) for a rolling-lobe air spring has on its rounded portion an annular, closed, concave, rounded holding recess ( 13 ) which has a circular arcuate shape. The plate is provided with the recess before surface treatment. A correspondingly shaped holding bead ( 16 ) in the upper flanging tool ( 3 ) engages in this holding recess and form-tightly holds the tool ( 3 ) and the flanged plate ( 1 ). In this way, sharp-edged holding grooves, which can damage the surface of the flanged plate, are unnecessary. The flanging method, the flanging device, the flanged plate and the rolling-lobe air spring provided with a flanged plate of the above type are described.

RELATED APPLICATION

This application is a continuation application of PCT patent applicationPCT/EP 2004/052744, filed Nov. 1, 2004, designating the United Statesand claiming priority from German patent application no. 103 55 441.6,filed Nov. 27, 2003, the entire contents of both applications beingincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a method for making a rolling-lobe air springhaving a rolling-lobe resilient member and a flanged plate having a rimand a base wherein the flanged plate is placed in a lower tool and anupper flanging tool presses the flanged plate into the lower flangingtool. The rim of the flanged plate is formed to define a torus and therim of the flanged plate successively encloses a bead of therolling-lobe resilient member. An apparatus is provided which has anupper and lower flanging tool for carrying out the method of making therolling-lobe air spring. The flanged plate has a rim and a base for arolling-lobe air spring and the rolling-lobe air spring has a rollinglobe and a flanged plate.

BACKGROUND OF THE INVENTION

Air springs, as they are used in the manufacture of motor vehicles forspring mounting wheel suspensions, include essentially a rolling-loberesilient member. The rolling-lobe resilient member is delimited at oneend by a cover plate and, at the other end, by a roll-off piston and soencloses an air spring volume within its interior space. Therolling-lobe flexible member itself comprises rubber or a rubber-likeplastic having attachment beads at its respective ends. The end of therolling-lobe flexible member disposed at the cover plate is usuallyattached by flanging and, for this reason, the upper cover plate is alsoknown as a flanged plate.

A flanged plate of this kind mostly includes an essentially planar baseand an annularly-shaped rim arranged perpendicularly to the base. Thetransition from the base to the rim of the flanged plate is provided bya convex arc portion having a radius clearly less than the perpendicularextent of the rim.

The flanging procedure itself corresponds to the swage flanging knownfrom form shaping technology. The flanged plate is disposed with itsopening facing downwardly in an annularly-shaped closed lower flangingtool open upwardly. The lower part of the lower flanging tool has anose-shaped projecting annular shoulder whose diameter is less than thediameter of the rim of the flanged plate. Referring to FIG. 3, aflanging tool is shown schematically. The flanged plate is identified byreference numeral 1 and the lower flanging tool by 2 and the upperflanging tool by 3. The nose-shaped annular shoulder is identified byreference numeral 4.

When flanging, the flanged plate is pressed from above by the upperflanging tool downwardly into the lower flanging tool. The lower edge ofthe rim of the flanged plate is bent inwardly by the nose-shaped annularshoulder of the lower flanging tool. The rim assumes the form of a toruswhich includes the upper-end attachment bead of a rubber rolling-lobeflexible member so that a tight and secure connection is establishedbetween the rolling-lobe flexible member and the flanged plate.

FIG. 4 shows a detail of a completed flanged rolling-lobe air spring 5and shows the result of such a flanging procedure. The rim 6 of theflanged plate 1 is formed to have a torus shape about the bead 7 of arolling-lobe flexible member 8. The base 9 of the flanged plate 1 isplanar.

The rim is pressed back toward the base by the pressure exerted whenpressing on the rim of the flanged plate. This operation is shown inFIG. 5. The flanged plate 1 is pressed against the upper flanging tool 3by the force F. In this way, a material flow into the base 9 of theflanged plate 1 results which leads to the situation that the base 9 ofthe flanged plate 1 bulges to be concave or convex and thereby makes theflanged plate 1 unusable. In order to avoid this, and according to FIG.6, the upper flanging tool 3 is usually equipped with holding grooves 10defining sharp edges which, at the beginning of the pressing, dig intothe surface of the flanged plate and so prevent the disadvantageousmaterial flow. However, the surface of the flanged plate 1 is damagedwhich operates disadvantageously on a corrosion protection layer of theflanged plate 1 because this layer is penetrated by the sharp edgesdefined by the holding grooves 10. An organic corrosion protection layeris therefore completely ineffective at this location and thereforecannot be used.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method for making arolling-lobe air spring wherein the flanged plate can be tightly flangedto the rolling-lobe flexible member without significant changes to theflanging tool described initially herein and without damaging thesurface of the flanged plate having a planar base.

The method of the invention is for making a rolling-lobe air springhaving a rolling-lobe resilient member and a flanged plate, the flangedplate having a base and a rim connected to the base via a convex arcuateportion of the flanged plate with the flanged plate being open facingtoward the rolling-lobe resilient member. The method includes the stepsof: placing the flanged plate in a lower flanging work tool; forming anannular continuous concave holding recess in the flanged plate roundedto have a shape corresponding to a circular arc when viewed in crosssection and the recess having a depth less than the thickness of theflanged plate; the holding recess being located in the region of theconvex arcuate portion and arranged in a complete revolution about theentire periphery of the flanged plate; coating the flanged plate with acorrosion protective layer; providing a convex holding bead, which isrounded to have a shape corresponding to a circular arc when viewed incross section, on an upper flanging work tool corresponding to theholding recess of the flanged plate; during the flanging operation, whenpressing down on the flanged plate utilizing the upper flanging worktool, bringing the holding recess of the flanged plate into contactengagement with the convex holding bead of the upper flanging work tool;and, forming the rim of the flanged plate form tight into a torus shapeto grasp the bead of the rolling-lobe resilient member by pressing theflanged plate into the lower flanging work tool utilizing the upperflanging work tool.

This method affords the advantage that, because of the engagement of theholding recess and holding bead, a material flow from the rim into thebase of the flanged plate is form tightly prevented without the surfaceof the flanged plate being damaged.

It is a further object of the invention to provide an apparatus forcarrying out the method of the invention for making a rolling-lobe airspring which makes possible a damage-free flanging of the flanged platehaving a planar base.

According to another feature of the invention, the upper flanging toolhas at least one annularly-shaped rounded convex holding bead whichcorresponds to the at least one concave holding recess of the flangedplate. The holding bead can, during the flanging process, be broughtinto engagement with the at least one concave holding recess of theflanged plate when pressing down the flanged plate utilizing the upperflanging tool.

This arrangement affords the advantage that the holding bead, which isconfigured without sharp edges, does not penetrate through the surfaceof the flanged plate; instead, the bead engages into the correspondingholding recess of the flanged plate and thereby acts form tight againsta material flow between the rim and the base of the flanged plate. Inthis way, damage to the surface layers of the flanged plate can beavoided.

According to another embodiment of the invention, the cross section ofthe at least one annularly-shaped convex holding bead of the upperflanging tool has a circular arc-shaped cross section having a radius ofthe circular arc between 2 mm and 30 mm.

This apparatus according to the invention affords the advantage that theflanged plate can be easily centered in the upper flanging tool becauseslight deviations from the ideal planar insert position of the flangedplate into the lower flanging tool compensate by themselves because ofthe circular arc-shaped form.

In a further embodiment of the invention, the convex holding bead of theupper flanging tool is arranged at an angle between 15° and 85° to thehorizontal.

This arrangement affords the advantage that the prevention of thematerial flow from the rim to the base is obtainable in a wide regionbecause of the geometric conditions and the material characteristics ofthe flanged plate.

It is a further object of the invention to provide a flanged platehaving a rim and a base for a rolling-lobe air spring which can beflanged maintaining a planar base without damage to its surface withoutsignificant changes to the flanging tool described initially herein.

The flanged plate of the invention includes: a rim; a base for arolling-lobe air spring; a convex arcuate portion connecting the rim tothe base thereby forming the flanged plate having a convex outer surfaceat the convex arcuate portion; an annular continuous concave holdingrecess formed in the flanged plate at the convex outer surface and theconcave holding recess having a depth less than the thickness of theflanged plate; a corrosion protective layer covering the flanged plateincluding the holding recess; and, the concave holding recess beingarranged in a complete revolution about the entire periphery of theflanged plate.

This flanged plate according to the invention affords the advantagethat, for a placed flanged plate, the holding beads in the upperflanging tool can be brought into contact engagement with the holdingrecesses of the flanged plate without damaging the surface of theflanged plate and, in this way, can form tight prevent a material flowfrom the rim into the base of the flanged plate. The holding beadscorrespond to the holding recesses and are configured to be rounded tohave a circular arcuate shape.

In a further embodiment of the invention, the cross section of the atleast one annularly-shaped concave holding bead has a circularlyarc-shaped cross section. The radius of the circular arc lies between 2mm and 30 mm.

This embodiment affords the advantage that the flanged plate can beeasily centered in the upper flanging tool because slight deviationsfrom the ideal planar insert position of the flanged plate into thelower flanging tool can be compensated automatically because of thecircular arc shape.

In a further embodiment of the invention, the concave holding bead isarranged in the region of the arc at an angle of between 15° and 85° tothe planar base of the flanged plate.

This affords the advantage that the prevention of material flow from therim to the base is achievable in a wide range with respect to geometricconditions and the material characteristics.

It is a further object of the invention to provide a rolling-lobe airspring whose flanged plate has a planar base after flanging to therolling-lobe flexible member without damage to the surface in the regionof the engagement between upper flanging tool and the flanged plate.

The rolling-lobe air spring of the invention includes: a rolling-loberesilient member having a bead at an end thereof; a flanged plateincluding a rim, a planar base and a convex arcuate portion connectingthe rim to the base; the flanged plate having a convex outer surface atthe convex arcuate portion; the flanged plate having an annularcontinuous concave holding recess formed therein at the convex outersurface; the holding recess having a depth less than the thickness ofthe flanged plate and being arranged in a complete revolution about theentire periphery of the flanged plate; the flanged plate having acorrosion protective layer applied in advance of a flanging operationwith the corrosion protective layer being applied so as to cover theflanged plate including the holding recess; and, the flanged plate beingdevoid of material flow between the rim and the planar base when theflanged plate is flanged to the bead of the resilient member when anupper flanging tool acts on the flanged plate by pressing downthereagainst with the holding recess being in contact engagement with aconvex holding bead of the upper flanging work tool.

In a further embodiment of the invention, the concave holding recess ofthe flanged plate of the rolling-lobe air spring has a circulararcuately-shaped cross section having a radius of the circular arcbetween 2 mm and 30 mm.

This embodiment affords the advantage that the flanged plate can beeasily centered in the upper flanging tool because slight deviations ofthe ideal planar placement position of the flanged plate into the lowerflanging tool are automatically compensated because of the circular arcshape. In this way, a uniformity of the grasping of the bead of therolling-lobe flexible member of the rolling-lobe air spring is improved.

In a further embodiment of the invention, the concave holding recess isarranged in the region of the arc at an angle between 15° and 85° to theplanar base of the flanged plate.

This affords the advantage that the prevention of the material flow fromthe rim to the base is achievable in a wide range with respect to thegeometric conditions and the material characteristics of the flangedplate.

With the solution of the invention, the rolling-lobe air spring has aplanar base because of the flanging of the flanged plate without a largeload on the surface while simultaneously preventing the material flowbetween rim and base of the flanged plate with the corrosion protectionbeing maintained. In this way, rolling-lobe air springs with organicallycoated flanged plates are possible without damage of the organicprotective layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawingswherein:

FIG. 1 shows a flanged plate according to the invention having a holdingrecess;

FIG. 2 shows the interaction of the holding recess and the upperflanging tool;

FIG. 3 shows a flanging tool according to the state of the art;

FIG. 4 shows a completed flanged rolling-lobe air spring according tothe state of the art;

FIG. 5 shows the bending of the base of the flanged plate according tothe state of the art; and,

FIG. 6 shows holding grooves defining sharp edges of an upper flangingtool according to the state of the art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 shows a portion of a flanged plate 1 of the invention in crosssection. The flanged plate 1 includes a base 9 and a rim 6. The base 9and rim 6 are joined to each other via a convex arcuate portion 11having a radius 12. In the region of the convex arcuate portion 11, theflanged plate 1 has a concave holding recess 13 having a radius 14 whichis produced during the manufacturing process of the flanged plate 1. Theradius 14 of the holding recess 13 is of the same order of magnitude asthe radius 12 of the convex arcuate portion 11. The holding recess 13 isarranged at a position angle 15 in the region of the convex arcuateportion 11 and is operatively connected in a form-tight manner to aholding bead 16 (FIG. 2) at the tool end for preventing a material flowfrom the rim 6 via the convex arcuate portion 11 into the base 9.

In FIG. 2, the interaction of the holding recess 13 and the upperflanging tool 3 is shown during flanging. The upper flanging tool 3 hasthe holding bead 16 which is configured to have a circular arc shapewhen viewed in section and is adapted to the radius 14 of the holdingrecess 13 of the flanged plate 1 and, during flanging, the holding bead16 engages precisely into the holding recess 13. In this way, thematerial flow referred to above is prevented.

It is understood that the foregoing description is that of the preferredembodiments of the invention and that various changes and modificationsmay be made thereto without departing from the spirit and scope of theinvention as defined in the appended claims.

1. A method of making a rolling-lobe air spring having a rolling-loberesilient member and a flanged plate, the flanged plate having a baseand a rim connected to the base via a convex arcuate portion of saidflanged plate with said flanged plate being open facing toward therolling-lobe resilient member, the method comprising the steps of:placing the flanged plate in a lower flanging work tool; forming anannular continuous concave holding recess in said flanged plate roundedto have a shape corresponding to a circular arc when viewed in crosssection and the recess having a depth less than the thickness of theflanged plate; said holding recess being located in the region of theconvex arcuate portion and arranged in a complete revolution about theentire periphery of said flanged plate; coating said flanged plate witha corrosion protective layer; providing a convex holding bead, which isrounded to have a shape corresponding to a circular arc when viewed incross section, on an upper flanging work tool corresponding to theholding recess of the flanged plate; during the flanging operation, whenpressing down on said flanged plate utilizing the upper flanging worktool, bringing said holding recess of said flanged plate into contactengagement with the convex holding bead of the upper flanging work tool;and, forming the rim of said flanged plate form tight into a torus shapeto grasp the bead of the rolling-lobe resilient member by pressing theflanged plate into the lower flanging work tool utilizing the upperflanging work tool.
 2. An apparatus for carrying out a method of makinga rolling-lobe air spring having a flanged plate, the flanged platehaving a concave holding recess, the apparatus comprising: an upperflanging work tool having a convex holding bead rounded to have a shapecorresponding to a circular arc when viewed in cross section; saidconvex holding bead corresponding to the concave holding recess of theflanged plate; and, wherein said convex holding bead can be brought intocontact engagement with the concave holding recess of the flanged plateduring the flanging operation when said upper flanging work tool pressesdown against the flanged plate.
 3. The apparatus of claim 2, whereinsaid convex holding bead is an annular bead having a shape correspondingto a circular arc when viewed in cross section and said circular arc hasa radius in a range between 2 and 30 mm.
 4. The apparatus of claim 2,wherein said convex holding bead of said upper flanging work tool isarranged at an angle of between 15° and 85° with respect to thehorizontal.
 5. A flanged plate comprising: a rim; a base for arolling-lobe air spring; a convex arcuate portion connecting said rim tosaid base thereby forming said flanged plate having a convex outersurface at said convex arcuate portion; an annular continuous concaveholding recess formed in said flanged plate at said convex outer surfaceand said concave holding recess having a depth less than the thicknessof said flanged plate; a corrosion protective layer covering saidflanged plate including said holding recess; and, said concave holdingrecess being arranged in a complete revolution about the entireperiphery of said flanged plate.
 6. The flanged plate of claim 5,wherein said concave holding recess has a shape corresponding to acircular arc when viewed in cross section; and, said circular arc has aradius lying between 2 mm and 30 mm.
 7. The flanged plate of claim 5,wherein said base is planar; and, said concave holding recess isarranged in the region of said convex arcuate portion to be at an angleof between 15° and 85° to said planar base.
 8. A rolling-lobe air springcomprising: a rolling-lobe resilient member having a bead at an endthereof; a flanged plate including a rim, a planar base and a convexarcuate portion connecting said rim to said base; said flanged platehaving a convex outer surface at said convex arcuate portion; saidflanged plate having an annular continuous concave holding recess formedtherein at said convex outer surface; said holding recess having a depthless than the thickness of said flanged plate and being arranged in acomplete revolution about the entire periphery of said flanged plate;said flanged plate having a corrosion protective layer applied inadvance of a flanging operation with said corrosion protective layerbeing applied so as to cover said flanged plate including said holdingrecess; and, said flanged plate being devoid of material flow betweensaid rim and said planar base when said flanged plate is flanged to saidbead of said resilient member when an upper flanging tool acts on saidflanged plate by pressing down thereagainst with said holding recessbeing in contact engagement with a convex holding bead of the upperflanging work tool.
 9. The rolling-lobe air spring of claim 8, whereinsaid concave holding recess has a shape corresponding to a circular arcwhen viewed in cross section and said circular arc has a radius in arange of between 2 and 30 mm.
 10. The rolling-lobe air spring of claim8, wherein said concave holding recess is arranged in the region of saidconvex arcuate portion at an angle of between 15° and 85° with respectto said planar base.